(以下英文内容摘自ansys help 文档。)
Weighted (available only as an objective function) distributes material so that the specified mean frequency formulation is maximized.
Reciprocal (available only as an objective function) is a mean frequency formulation that defines a smoother function than Single. It is best used when two modes whose eigenfrequencies occur in the given mean formulation exchange their orders during optimization. The eigenfrequency that is closest to the target frequency (set with Targval) experiences the largest increase and is maximized.
Euclidean Norm Formulation (available only as an objective function) is used to shift single or multiple eigenfrequencies up. The mean eigenfrequency is utilized to smooth the optimization process. This must be used as the objective where the optimization procedure distributes material so that the mean frequency is minimized.